Derivatization and mass spectrometry

E. Lattova and H. Perreault, Profiling of AMinked oligosaccharides using phenylhydrazine derivatization and mass spectrometry, J. Chromatogr. A, 1016 (2003) 71-87. 

D. Momcilovic, H. Schagerlof, B. Wittgren, K.-G. Wahlund, and G. Brinkmahn, Improved chemical analysis of cellulsoe ethers using dialkylamine derivatization and mass spectrometry, Anal. Chem., 77 (2005) 2948-2959. 

Detection of Disulfide Linkage by Chemical Derivatization and Mass Spectrometry... 

Other spectroscopic methods such as infrared (ir), and nuclear magnetic resonance (nmr), circular dichroism (cd), and mass spectrometry (ms) are invaluable tools for identification and stmcture elucidation. Nmr spectroscopy allows for geometric assignment of the carbon—carbon double bonds, as well as relative stereochemistry of ring substituents. These spectroscopic methods coupled with traditional chemical derivatization techniques provide the framework by which new carotenoids are identified and characterized (16,17). 

A large number of silylating agents exist for the introduction of the trimethylsilyl group onto a variety of alcohols. In general, the sterically least hindered alcohols are the most readily silylated, but are also the most labile to hydrolysis with either acid or base. Trimethylsilylation is used extensively for the derivatization of most functional groups to increase their volatility for gas chromatography and mass spectrometry. 

Maximum benefit from Gas Chromatography and Mass Spectrometry will be obtained if the user is aware of the information contained in the book. That is, Part I should be read to gain a practical understanding of GC/MS technology. In Part II, the reader will discover the nature of the material contained in each chapter. GC conditions for separating specific compounds are found under the appropriate chapter headings. The compounds for each GC separation are listed in order of elution, but more important, conditions that are likely to separate similar compound types are shown. Part II also contains information on derivatization, as well as on mass spectral interpretation for derivatized and underivatized compounds. Part III, combined with information from a library search, provides a list of ion masses and neutral losses for interpreting unknown compounds. The appendices in Part IV contain a wealth of information of value to the practice of GC and MS. 

Baker GB, Coutts RT, Holt A. 1994. Derivatization with acetic anhydride applications to the analysis of biogenic amines and psychiatric drugs by gas chromatography and mass spectrometry. J Pharmacol Toxicol Methods 31 141. 

Other more conventional detectors that might ostensibly outperform CD in selectivity are nmr and mass spectrometry, and in fact they do for the analysis of diastereomers, although quantitation is a much more difficult task. They cannot compete with chiroptical methods for the distinction between enantiomers. In nmr detection, derivatization to diastereomers is a prerequisite to enantiomer analysis, and chiral forms of lanthanide reagents can been used with good effect [16,17]. For the analysis of mixtures by either nmr or mass spectrometry, total chromatographic separation is a necessity, so the completeness of the baseline separation is the limiting step not the detector. In contrast CD can be applied to the analysis of enantiomers in mixtures in methods that require no prior separation. 

Separations by GC are very popular for non-polar organic compounds. Prior to the separation however extraction from the sample and preconcentration have to be performed as well as derivatization. The last step is usually done by addition of Grignard reagent (RMgX) and its excess after the process is removed by acid addition. As detectors after GC separation successfully are used ICP-AES (for N, P, S, C, Br, Cl, Hg, Zn, Pb) with detection limit in the pg range atomic fluorescence and mass spectrometry. 

As described in more detail in Section 13.3.2, the main analytical techniques that are employed for metabonomic studies are based on nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). The latter technique requires a preseparation of the metabolic components using either gas chromatography (GC) after chemical derivatization or liquid chromatography (LC), with the newer method of ultra-high-pressure LC (UPLC) being used increasingly. The use of capillary electrophoresis (CE) coupled to MS has also shown promise. Other more specialized techniques such as Fourier transform infrared spectroscopy and arrayed electrochemical detection have been used in some cases. 

The widespread use of gas chromatography and mass spectrometry necessitated fast, reliable and simple new derivatization techniques. Apart from silylation, most procedures for the formation of ethers from alcohols do not fulfil these requirements, but several useful reagents, most of them commercially available, have been introduced for rapid alkylation of the more acidic functions. 

Pentafluorobenzyl- chloroformate 2.16.1 Derivatization of tertiary amines for ECD-GLC analysis and mass spectrometry Convenient introduction of fluorine when perfluoro acid chlorides or anhydrides cannot be used... 

I,2,3,4,5,6)- Pentafluorobenzyl- hydroxylamine hydrochloride 2.16.2 Derivatization of steroids [26] and other ketones for ECD-GLC analysis and mass spectrometry Convenient fluorine-introducing alkylation for ketones... 

This chapter has concentrated on only the major derivative classes employed in GC-MS, and only a few examples of each could be mentioned. However, the literature, including the other chapters of the present handbook, contains an abundance of references and descriptions of other derivative types, many of which will have hidden mass spectrometric potential for particular applications. Trace analyses have been covered in depth for steroids [202] and cannabinoids [203] and in the application of NICI to drugs [204] and neurotransmitters [205]. A recent volume [206] includes a number of specialist chapters devoted to the application of mass spectrometry in different areas of biomedical research. It can be consulted for more in-depth information of work done with particular analyte classes, and contains a short overview of chemical derivatization for mass spectrometry, including some GC-MS examples [207], Comprehensive reviews by Evershed, covering developments and new applications of GC-MS, contain many references to derivati-... 

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